So one of the most common complaints that parents of autistic kids have is "oh no, my kid is too loud/too aggressive" and "he is hurting my ears/hurting me physically".
I am now 23 years old. I need to scream and punch things now, sometimes. I needed to scream and punch things in third grade, sometimes.
Instead of denying the legitimacy of this way of expression, lets see how people who have these needs can do these things in a safe manner that doesn't bother anyone.
The way I did it and still do it is that when I need to punch something, I punch a pillow or mattress on my bed.
When I need to scream, I scream into my pillow.
When I was even younger, my parents (had the monetary privilege to be able to have) bought an inflatable weighted punching bag.
I punched these things. I punched them very hard.
In regard to the pillow, I can scream into it until screaming is no longer possible.
What purpose do these actions serve? They vent troublesome emotions. They allow the expression of sensations which feel locked within my body screaming to get out.
I think a good alternative to a pillow for some children may be a large stuffed animal to scream into.
This behavior is not problematic as many professionals tell you. It is merely an alternative method of expressing difficult feelings and senses.